This invention relates to an improved apparatus, system and method for removing liquid rolling mill coolant from moving metal strip. More particularly it is concerned with removing liquid coolant from the side marginal edges of continuously rolled heavy gauge flat metal strip products such as flat metal strips or sheets of aluminum and aluminum alloys. As indicated in U.S. Pat. No. 4,477,287 issued Oct. 16, 1984, various devices have been developed in the past for removing liquid coolant, and in particular water based liquid coolant from rolled aluminum and aluminum alloys to prevent the formation of what is commonly referred to in the art as "water stain". The method and equipment as disclosed in this patent involves a unique arrangement of vacuum creating units and air knives which remove substantially all of the liquid rolling mill coolant from the top and bottom surfaces as well as the edges of the strip, when the metal strip has a guage or thickness below 0.050" (1.27 mm).
Despite the fact that the method and equipment disclosed in the aforesaid patent, which include the customary use of a billy or idler roll, perform satisfactorily in removing liquid coolants from some metal strip such as aluminum strip having a thickness or gauge of less than about 0.050" (1.27 mm), there are occasions where it is not practical to use such a device. For example, when relatively heavy gauge metal strips such as aluminum and aluminum alloy strip having a gauge of about 0.050" (1.27 mm), and above are rolled and then subjected to liquid coolant removal operations including strip edge coolant removal a billy roll is relatively useless and impractical. This is because billy rolls do not serve to present substantially flattened heavy gauge aluminum strip to coolant removal units due to the inability of such heavy gauge aluminum strip of 0.050" (1.27 mm) thickness and beyond to conform properly to the surfaces of such billy or idler rolls as a consequence of their thickness. Thus at times there may be some slight deviations in heavy guage strip or sheet flatness which can cause interference with current edge liquid coolant removal equipment such as that disclosed in the aforementioned patent and thus detract from overall equipment efficiency. For example, a minor edge wave in 0.125" (3.175 mm) gauge or thickness of rolled aluminum sheet can be as far as 1" (25.4 mm) from the roll on which it is being wrapped or passed.
For the purposes of this invention the term "heavy gauge" strip or sheet as used in the specification and claims shall mean aluminum and aluminum alloy strip having a gauge thickness of at least about 0.050" (1.27 mm) up to at least about 0.249" (6.32 mm) the dividing line between aluminum and aluminum alloy sheet and plate.
Accordingly it is a primary purpose of the instant invention to provide an improved method, system and apparatus for removing liquid coolant from the marginal side edges of a moving metal sheet or strip.
It is another purpose of the instant invention to provide a unique method, system and apparatus for effecting efficient removal of a liquid such as liquid coolant from the edge of a moving heavy gauge sheet or strip.
It is a further purpose of the instant invention to provide an improved method, system and apparatus for effecting efficient removal of a liquid coolant from the edges of a fast moving strip of metal such as an aluminum metal alloy strip regardless of variations in the normal rolled strip or sheet width and/or the location of the instant coolant removal units relative to a rolling mill.
It is another purpose of the invention to provide improved rolling mill strip edge liquid coolant removal equipment that can be readily integrated and operated with existing metal rolling mill equipment arrangements including top and bottom strip surface liquid coolant diversionary or removal units.
It is still another purpose of the instant invention to provide a unique method, system and apparatus for producing and presenting for coiling substantially water stain free aluminum and aluminum alloy sheet particularly in the heavy gauges.
These and other purposes are achieved in the instant invention by use of unique combination edge contacting wiping roller and vacuum units arranged adjacent to and in contact with the side marginal edges of a fast moving metal strip. These units operate to effect substantially complete removal of any residual liquid coolant that may still be present on or cling to the side marginal edges usually, if at all, in heavy gauge metal strip and subsequent to a prior coolant diversion or removal operations.
One preferred embodiment of the invention contemplates that the instant units would be used in conjunction with any suitable metal strip coolant deflection blow-off system where a gaseous medium such as dry air is directed simultaneously over and across the top and bottom surfaces of the strip and toward the side edges of the strip so as to inhibit among other things deleterious rewetting of the strip while diverting liquid coolant into side collection troughs. When the instant roller-vacuum units are operated in conjunction with such strip surface blow-off systems substantially coolant free strip will have been processed and passed to the usual coiling mechanisms.
The type of top and bottom surface blow-off equipment that might be used is disclosed to some extent in U.S. Pat. No. 3,192,752 issued July 6, 1965.